Drill



Aug. 29, 1944.v A A. 5. EDWARDS 2,356,921

DRILL Filed Feb. 5, 1943 Patented Aug. 29, 1944 UNITED f STATES PATENT OFFICE DRILL Arthur 0. Edwards, Villanova, Pa. Application February 5, 1943, serial No. 474,771 claims (01.255-64) The object of my invention is to provide a bit, adapted for connection with a drill shank, or with an adapter carried by the drill shank, which willi provide an outlet for drilling uid through a Vcentral bore, supplemented by provision for side escape of drilling fluid, to thereby, during use, reduce or eliminate clogging of the drill and eifect better cooling of the drill. A further object of the invention is to so construct a bit having these advantages that it may be made at minimum cost in a simple forging operation.

A bit embodying my invention is provided with a dovetail tenon slidable into a dovetail groove in the drill shank or in an adapter secured to the drill shank; the tenon being provided with a recess opening in its endface and extending from side to side thereof and of a depth approximating the height of the tenon, thereby forming in effect two dovetail tenons spaced apart by the recess specified. The bit is provided with a central bore extending therethrough from the base of said recess and affording a main passage for flow of drilling fluid. This central bore is of a diameter substantially less than the width or depth of the recess. The described construction makes it possible to make this central bore of a length not exceeding twice the width of the recess in the tenon. I

These features of my improved bit greatly facilitate the discharge of drilling fluid through the bit and minimize danger of clogging: first, because the central bore through the bit is materially shortened in length; second, because over a third of the length of the fluid passage through the bit comprises an enlarged uidcontaining chamber, formed by the described recess, between the bore hole in the drill shank (or adapter) and the bore hole in the bit; and third, means are provided, supplementing the liquid discharge through short bore of the bit, for side escape of drilling iiuid between the sides and face of the tenon and the side wall and base of the dovetail recess in the drill shank or adapter.

The described construction has other` advantages. length of the central bore of the bit and the width of the recess in the tenon, the said bore can be readily punched during manufacture, as contrasted with the usual method of manufacture, which necessitates drilling. The bit can thus be readily forged at minimum cost.

In the drawing: Fig. 1 is a vertical sectional view disclosing one means of connecting the bit,

Owing to the proportion between the' through an adapter, with a drill shank. Fig; 2 is a vertical sectional view, taken at right angles to Fig.-1, of the bit applied to an adapter. Fig. 3 is a perspective View of the bit.

Referring rst to Fig. 1: The drill shank or stock m is 'externally threaded at its front end. An adapter ois provided with a similar internally threaded recess and is thus adapted for en- Vgagement with the drill shank.

The adapter is provided with a dovetail groove extending diametrically across the front of its body.

The drill bit comprises a body having a nurnber of 'radial wings g (four are shown) at equal arcuateV distances' apart, and, extending beyond, and diamctrically of the bOdy of the bit, a dovetail tenon h. The bit is applied to the adapter by sliding the dovetail tenon transversely into the dovetail groove in the adapter.

The shank m, adapter o and bit are provided with bores, n, r and lc respectively, for passage of drilling fluid extending through their longitudinal centers, the bores centralizing when the parts are assembled.

The dovetail tenon h is cut away at its center to form a semi-cylindrical recess i. The depth of the recess is, preferably, nearly equal to the height, measured longitudinally of the drill, of the dovetail tenon, thereby shortening the length of the bore 1c to not over twice the extreme Width and, preferably also, not over twice the depth, of the central recess i in the tenon h, and providing, between the bore 1c and the bores in the adapter and shank, a chamber whose dimensions, both longitudinally and laterally of the tenon h, substantially exceed the diameter of these bores. This recess, together with the shortened length of the bore Ic, substantially facilitates the free exit of water and slurry. And such exit is further facilitated by the side escape of fluid between the sides and face of the tenon h and the side walls and base of the dovetail recess in the adaptera.

In bits heretofore known the bore through the bit does not always allow free exit of water and slurry. With the object of insuring more free exit, vbits are often provided with side oriiices, instead of a straight-through central bore. While the usual central bore may be retained and side orifices may be provided as supplementary fluid outletsy such an expedient is open to the objection of weakening the bit and also to the objection of complicating and adding to the expense of its manufacture. In my construction the aligning central bores extending through the drill, adapter and bit do not aord a continuous narrow channel; the bore in the adapter vand the bore in the bit being separated bythe enlarged space formed by the recess i, which space greatly shortens the length of the bore lc, allowing a more free fluid discharge, While also allowing a certain proportion of the drilling fluid to escape between the tenon h and the Walls of the groove in the adapter, as above explained; thereby greatly facilitating the exit of drilling uid and slurryand allowing for better cooling of the bit. This construction is found to be admirably adapted to prevent clogging and to be particularly useful when the bit is used in hard rock formations, ravelled rock, asbestos mines and the like. Also, as hereinbefore explained, instead of drilling the bore k it may be readily forged at a minimum cost.

It will be understood that the invention does not depend for its novelty upon the means, disclosed in `Fig. 1, for connecting the bit with the drill shank or stock. The bit may be applied to the adapter and the adapter may be secured to the shank in any manner; or the bit may be secured directly to the drill shank: provided, only, that the adaptery or the drill shank if the bit is directly secured thereto, shall be provided with a dovetail groove into which the tenon of the bit may easily slide.

What I claim and desire to protect by Letters Patent is:

1. A drill bit comprising a body and dovetail tenon and provided with a central bore extending through the body of the bit for flow of drilling fluid therethrough and provided also with a recess opening in the rear face of the tenon and extending from side to side thereof and communicating with said bore, said recess at its mouth being of a width substantially greater than the diameter of the end of said bore opening into said recess and not less than half the length of said bore, thereby facilitating discharge of drilling uid through the bore while also providing side outlets for drilling fluid outside and along the two end parts of the tenon and at the same time effecting better cooling of the bit.

2. A drill bit comprising a body and dovetail tenon and provided with a central bore extending through the body of the bit for flow pf drilling fluid therethrough and provided also rwith a. recess opening in the rear face of the tenon and extending from side to side thereof and communicating with said bore, said recess at its mouth being of a width substantially greater than the diameter of the end of said bore opening into said recess and not less than half the length of the bore and of a depth approximating the height of the tenon, thereby facilitating discharge of drilling fluid and simplifying and reducing cost of manufacture substantially as described.

3. A drill bit comprising a body having a central bore for flow of drilling fluid therethrough and two dovetail tenons whose outer corners are at equal distances from the center line of said bore and are spaced apart a distance substantially greater than the diameter of the bore and not less than half the length of said end of the bore opening into the space between said tenons.

4. A drill bit comprising a body provided on its under face with cutting teeth and on its upper face with two radially extending and diametrically aligning dovetail tenons spaced apart to form a space centrally positioned in said upper face, and provided also with an axial bore for flow of drilling fluid extending through the bit body from the under face thereof and at its upper end opening into, and communicating with, said space.

ARTHUR O. EDWARDS. 

